4 D Canadian Arctic Expedition, 1913-18 



two centimeters only. Growth is exceedingly slow, and the likelihood of mechan- 

 ical injury remote. Bones decay very slowly and there is no evidence that the 

 lichen covering is contributive. Driftwood thrown beyond the reach of the 

 water soon becomes covered with a varied lichen growth, the wood merely 

 weathering and not decaying. The tundra formations furnish an interesting 

 study because of the many generations of musci and lichens that go to make up 

 the mass of tussock or expanse. In many places through the Barren Ground 

 region and the Alaskan peninsula, the ground is covered to the depth of a foot 

 or more with the debris of successive generations of lichens and mosses of which 

 only the uppermost layer is living. From an ecological point of view, with the 

 rock lichens there are two pioneers, Caloplaca miniata preferring smooth stones, 

 and Rhizocarpon geographicum preferring the rough ones. Both smooth and 

 rough stones if beyond the action of the waves eventually become covered with 

 an indiscriminate coating of Lecidea, Lecanora, Biatorella, and other closely 

 adherent species. A peculiarity noticed in the course of my examination of the 

 crustose forms is the great number of vagrant apothecia interspersed with the 

 better developed lichens. These apothecia were without trace of visible thallus, 

 and belonged for the most part to the genera Caloplaca, Rinodina, Lecanora, 

 and Buellia. 



Darbishire found in his examination of the Fram lichens that old bones 

 bore Lecanora Hageni, L. varia, Rinodina turfacea, and Buellia parasema. No 

 Lecanora varia occurs on the bones of our material, nor has it been observed on 

 any other support. Buellia parasema was not detected, but Buellia myriocarpa 

 was noticed. 



On driftwood Darbishire found Caloplaca cerina, C. citrina, C. junger- 

 manniae, Lecanora epibryon, and Buellia myriocarpa. Caloplaca citrina was not 

 present in any of our material, but the other species were observed. A rather 

 curious fact may here be noted, that Lecanora polytropa or L. polytropa intricata 

 were not to be found on either rocks or bones. 



A comparison of results, in number of lichens collected by the Canadian 

 Arctic expedition (93) and herein listed, with the accomplishment of other 

 expeditions in adjacent regions may be of interest. ^ 



Professor John Macoun visited the Yukon region in 1902 and from his 

 material 103 species and varieties were separated. It is found that 33 are com- 

 mon to both districts. 



Sir John Richardson visited the Mackenzie valley in 1826 and his lichens 

 were identified by Leighton. One hundred were enumerated, and 27 are com- 

 mon to both regions. 



The Second Norwegian Polar expedition of 1898-1902 visited Greenland, 

 Ellesmere and King Oscar lands. The number of species differentiated by 

 Darbishire is 161, and the number common to both regions does not exceed 40. 



Alaska has been variously explored and nearly all of the lichens enumerated 

 in this list have been found on its mainland or islands. 



From Greenland 338 lichens have been listed, and 60 are common to 

 Greenland and the region covered by Canadian Arctic Expedition. Labrador 

 possesses 21 species in common, and Newfoundland 30. 



'The lichens of the Canadian Arctic Expedition were collected by Mr. Frita Johansen, unless other- 

 wise stated. 



When not otherwise stated the localities given are in Northwest Territories, Canada. For exact 

 position of localities see Vol. V. part A, pp. 5-6. 



